Good afternoon. Welcome to the
Get the Fact webinar series.
Today's topic is
Allium Vegetables and their effects on Colorectal Cancer.
Allium vegetables include garlic,
onion, leek, chive, and shallot, and etc.
For centuries, raw and cooked and dried allium vegetables
have been used as a food ingredient
and medicinal component.
In this webinar, we will review
potential anti-colorectal cancer effect
of allium vegetables.
I will start
with a brief background about colorectal cancer,
then allium vegetables including
their major bioactive components
like organic sulfur compound in food and supplement,
and then their possible entire carcinogenic mechanisms
and effects on colorectal cancer.
This figure shows
sections of the large intestine.
The large intestine begins with the cecum,
the place receive the undigested food
from the small intestine.
Then ascending colon extends upward,
and then transverse colon crosses
from the right to the left side of the body,
and then descending colon goes down,
and sigmoid colon is
the final section of the colon and lead to the rectum.
Colorectal cancer is a cancer that
starts in the colon or the rectum,
and these cancers can also be named
colon cancer or rectal cancer,
depending on where they start.
The colon cancer and the rectal cancer are
often grouped together because
they have many features in common.
This figure shows a cross section of colon,
so inner lining and showing here called the mucosa,
and that's the layer where
nearly all colorectal cancer starts.
The next layer called the submucosa,
and then a thick muscle layer,
then the outer layer is called the serosa.
That's the wrapping of the colon.
Colon cancer or colorectal cancer
usually begins as a non-cancerous growth
called the polyp that develops on
the inner lining of the colon or rectum,
and grows slowly over a period of time as
often takes more than 10 or 20 years.
There are two types of polyps:
an adenomatous polyps and hyperplastic polyps.
Adenomatous polyp also called the
adenoma is the most common type.
In about 30 to 50 percent of all individuals will
develop one or more adenomatous polyps.
Although all adenomatous polyps
have the potential to become cancerous,
less than 10 percent is progress to invasive cancer.
As an adenomatous polyps becomes bigger,
the chance of becoming cancerous increases.
The cancer arising from
the inner lining of
the colorectum is called the adenocarcinoma,
accounts for about 96 percent of all colorectal cancer.
Another type of polyps.
The hyperplastic polyps and inflammatory polyps.
Hyperplasia means they're fast growing.
They are growing really fast.
Although they are growing rapidly,
the hyperplastic polyps are
considered to be low risk of becoming cancerous.
Inflammatory polyps are mostly found in people with
inflammatory bowel disease such as
Crohn's disease or ulcerative colitis.
An inflammatory polyps are unlikely to become cancer.
This chart is from the American Cancer Society.
They estimated the new cancer cases in the US in 2019.
The colorectal cancer is
the third most common cancer
diagnosed in both men and women.
The American Cancer Society estimates for the number of
colorectal cancer cases for this year,
97,220 new cases of colon cancer
and 43,030 new cases of rectal cancer.
The overall, the lifetime risk
of developing colorectal cancer is about
one in 22 for men and then one in 24 for women.
This chart shows the cancer mortality this year.
Colorectal cancer is the third leading cause of
cancer in both men and women.
It was expected to cause about
50,630 deaths during this year,
and the death rate from this disease has been
dropping in both gender for several decades.
Better detection method and
improved treatment have contributed to this change.
Now, polyps are being found more often by
screening method and also removed and
treated before they can develop into cancers.
Many people with
colorectal cancer may not experience
any symptom in the early stages of the disease,
which is why screening is very important.
When symptoms appear, they will vary from
one person to another depending on the cancer stage.
They include a change
in bowel habits including diarrhea or constipation,
or change in the consistency
of stool that last longer than one month.
Rectal bleeding or blood in stool,
and persistent abdominal discomfort such as cramp,
and gas, or pain.
Feeling that your bowel doesn't empty completely,
and weakness or fatigue,
and unexplained weight loss.
If anyone notices any
of these symptoms, better see a doctor.
In most cases, it's not
clear what causes colorectal cancer.
There are several risk factors associated with
increased the chance of
developing polyps or colorectal cancer.
This slide shows risk factors we cannot change.
Younger adults can get it,
but it's much more common after age 50.
If an individual have a history of adenomatous polyps,
that person is having increased
risk of developing colorectal cancer.
If an individual has had
colorectal cancer at younger ages,
that person is more likely to develop
new cancers in other parts of the colon or rectum.
If an individual has a inflammatory bowel disease,
the risk goes up.
A family history of
colorectal cancer or adenomatous polyps,
that will increase the chance to
get developing colorectal cancer.
Having an inherited syndrome,
that would increase the risk,
so there are many types of
inherited conditions associated with colorectal cancer.
The most common inherited syndromes are
Lynch Syndrome and familial adenomatous polyposis.
Lynch syndrome is the most common one,
accounting for about 2-4 percent
of all colorectal cancers.
In most cases, this disorder is caused by
a gene mutation on the gene called MLH1 or 2.
These genes normally help repair DNA damage.
Those are the gene controlling that makes
sure your genetic information are replicated correctly.
Colorectal cancer link to this syndrome tend to
develop at relatively younger ages,
and familial adenomatous polyposis is caused by
mutation on the gene called the APC gene,
which is a tumor suppressor gene.
About 1 percent of
all colorectal cancer are caused by this condition.
In most common type of familial adenomatous polyposis,
hundreds and thousands of polyps can
develop in a person's colon and rectum,
often starting at a very young age,
like 10 or 12 years old.
By age 40, almost all people with this syndrome,
they will develop colorectal cancer.
In certain racial and ethnic background
also appears as a risk factor.
African-Americans have
the higher colorectal cancer instances
and that's rare than other racial group in this country.
The reasons for this are not fully understood.
The Jews of Eastern European descendant have one of
the highest colorectal cancer risk of
any ethnic group in the ward.
People with the type 2 diabetes have
an increased risk of colorectal cancer.
People who have either radiation therapy for
their health conditions have
an increased risk for this disease.
There are also risk factors we can change.
If people are overweight or obese,
their risk of developing or dying from colorectal cancer
is higher in both men and women,
and people who are not
physically active tend to have
a higher chance of developing colorectal cancer.
Diet high in red meat and
processed meat increase the risk.
Cooking meat at very high temperature,
like frying, boiling, and grilling,
those cooking process can create
carcinogen which is a chemical
that might increase the cancer risk.
That cooking process and
cooking method can contribute to the condition.
Long-term smokers have a higher risk
to develop and die from
this disease and heavy alcohol use
have been linked to the colorectal cancer.
After colorectal cancer diagnosis,
stage over these stages will be examined to this side,
that's the treatment options.
The size of the tumor will be examined to see how
far the cancer has grown
into the wall of the colon or rectum.
This spread to nearby lymph node and the invasion or
transfer to other site called
metastasis will be also examined.
There are five stages.
Stage 1 and stages one through four.
Stages 1 and 2,
cancers are contained to the wall of
the colon and possibly on nearby tissue.
Stage 3 cancer has spread from
the colon to nearby lymph nodes,
but not to other parts of the body.
At stage 4, the cancer has spread to other organs.
Once cancer form in
the inner lining of the large intestine,
it can grow deeper into the wall
and cancer cells typically
spread into nearby lymph nodes,
which play key roles in immune function.
Cancer cells can also go in
blood vessel to other organs and tissues,
such as the liver,
lungs and the abdominal area.
For screening, there are two main groups:
visual exams and stool-based test.
Visual exams can provide
the two-dimensional or three-dimensional images of
a colon and rectum and that can
detect the structural abnormalities.
They are performed at health care facilities
and stool-based test-check the stool for signs of cancer.
Cancers' tumors and some large polyps
bleed into the intestine.
This blood may not be visible to our eyes,
but stool test can detect it.
The stool-based test are not invasive,
and can be done by yourself at home.
But they need to be done more often.
They're colonoscopy or sigmoidoscopy
in combination with the fecal occult blood test,
are commonly used screening method.
Colonoscopy is the most common,
the visual screening tests in this country.
This procedure or a loss for
direct visual examination of the entire system,
I mean colon and rectum
system and it's performed for screening
purposes and as well as after
abnormal results from other screening tests.
Before undergoing colonoscopy, patients are instructed to
take special laxatives to
cleanse their colon rectum completely,
so the intestinal lining can be thoroughly examined.
During the exam, their colon is inflated toward the air,
then colonoscope is inserted into
the anus and move slowly through the rectum and colon.
Colonoscope has a light and
small video camera on the end,
which allows for the detection and removal
of polyps with a wire loop or electric current.
If the results are normal,
they exempt does not need to be repeated
for 10 years in average risk patients.
Flexible sigmoid scope is very similar to
colonoscopy except that screens only sigmoid colon,
so last part of the colon compared to colonoscopy,
it's fairly quick and has fewer complications,
and requires a minimal bowel preparation
and does not need sedation.
It was recommended every five-years,
and it's slightly more effective when
combined with blood testing.
In quiet base,
the fecal occult blood test
is to detect the blood in the stool,
as I mentioned before.
This test requires the annual testing of
a three samples from consecutive bowel movements.
This test doesn't require bowel cringing, non-invasive.
It can be done by yourself and slightly more
effective when combined with
a flexible sigmoidoscopy every five years.
If you want to know more
about the other screening method,
you can watch the webinar presented in January.
The American Cancer Society recommends that
people at average risk of colorectal cancer start
regular screening at age 45 through 75
and for people ages 76 through 85,
the screening decision should be
based on that person's preferences,
and people over 85 should no
longer get their colorectal cancer screening.
US Preventive Services Task Force guideline
also recommends that people age
50 through 75 at average risk starts regular screening.
People at higher risk,
including people whom I mentioned earlier,
the American Cancer Society recommends to
start colorectal cancer screening before age 45
and need to be screened more often and possible
to get other specific test
to make sure it's not recurring.
For treatment options, there are two groups,
local treatment and systemic treatments.
Local treatment includes surgery,
ablation and embolization, and radiation therapy.
Still surgery remains the best chance of a cure.
Surgery is standard for stage
1 through 3 colorectal cancer,
where the tumor is considered the local.
Then during surgery, tumor will be
removed as part of the polyps or a part
of a colon or rectum and
the surrounding tissues including
fats and lymph node will be removed.
The healthy section will be reconnected and rerouted.
Ablation and/or embolization might be used to
destroy small cancerous cells
spread to a nearby or other organs.
Radiation therapy uses high-energy rays
of chest X-ray or particles to kill cancer cells.
It may be used alone or in
combination with the other therapies to shrink
tumor size before surgery or
to destroy any remaining cancer cells after chemo.
Radiation can also be used to reduce the size,
to make patient more
comfortable even when the cancer cannot be removed,
tumor cannot be removed.
Colorectal cancer can also be treated
with drugs called the systemic
treatment because the drugs
can deliver to the whole system.
Depending on the type of a colorectal cancer,
different types of drug might be
used such as chemotherapy,
targeted therapy, and immunotherapy.
In most chemotherapy, medicines
are taken as a liquid injection into
vein and the drug travels in
the blood and attack
cancer cells throughout the entire body.
The researchers have learned more about
the gene and protein changes in
cancer cells that are
causing colorectal cancer or
involved in their metabolism.
New treatments were developed
called the targeted therapy,
which are designed to target these changes.
In general, tumors get nutrient
from blood in order to grow rapidly.
Drugs that inhibit blood vessel formation
can be used to reduce the blood supply to tumor,
and tumors tend to express
higher level of a growth factor receptors.
Drugs that inhibit or block
these growth factor receptors can be
used to inhibit the tumor growth.
Targeted therapy drugs can be used either along with
the chemo or by themselves if
the chemo is not working anymore.
Immunotherapy uses drugs to help
a patient's immune system
better recognize and destroy cancer cells.
Let's move on to allium vegetables.
Allium is the Latin word for garlic.
Allium is part of allium genus,
frequently referred to as the onion genus.
This genus includes approximately 500 species,
including garlics, onions, shallots,
and leek, and chives, scallions etc.
Allium vegetables are widely cultivated
all over the world and they have been used
for the cooking and the medicinal purposes
in many cultures for over 4,000 years.
Ancient medical texts from Egypt, Greece, Rome,
China, and India, they cite
the therapeutic application for allium vegetables.
Garlics are native to Central Asia
and they are one of the oldest
cultivated plant in the world.
Garlics are perennials, grow as bulbs,
which are made up of cloves.
Garlics are an important culinary spice and
a constituent of the traditional medicine
for thousands of years.
Garlic has the strongest flavor of all the alliums.
Garlic is a rich source of Organosulfur compound,
which are thought to be responsible
for garlic flavor and aroma,
as well as its potential house benefit.
I'll get back to
the Organosulfur compound a little bit later.
Onions have been cultivated for
thousands of years and originated
in the East and Central Asia,
but now grows all over the world.
They were grown not only for
use in cooking but for their antiseptic qualities.
In Egypt, onions were used in
mummification and they even
buried onions with the Pharaohs,
and believing that their round,
ring shape was symbolic of eternity.
Onions were also once used as a currency in middle ages.
The bulbs and the leaves onions
have a wide variety of flavor,
textures, and colors and therefore, many culinary uses.
Onions may have a yellow, white, and red,
or purple skin, and the majority of
onions purchase at the supermarket are yellow onions.
Pungent yellow onions are the best for
long-term storage and great addition to soups and stew.
While red onions are very sweet and good for raw
in salads and sandwiches or for topping,
but not good for long-term storage.
White onions or pearl onions are the tiniest of
bulb onions and are
the top choice for boiling and pickling.
Like garlic, shallots grow as bulbs in clusters,
usually two but occasionally as many as 10 cloves.
Most often they are
golden brown color and
they may also have reddish or gray.
Sometimes shallot flavor is
described as a blend of sweet onion and
garlic and their taste is somewhat
finer and less pungent than yellow onions,
and makes them a favorite of gourmet chefs.
They are commonly used in cooked dishes or pickle.
Many people think that
scallions are a type of onion, but in fact,
they are simply the immature plant of
any bulbing onion harvested
before the bulb is fully formed.
The scallions have a milder taste
than other onion variety.
Leeks are the largest member of the allium family.
It look like a gigantic scallions or green onions.
They may grow up to two feet long and two-inch diameters,
and they do not form a bulb.
France, Belgium, and Netherlands
lead the world in leek production.
The leeks are often featured in their cooking.
Leeks has a subtle earthy flavor and
milder fragrance than onion and garlic.
So they are a good complement to potatoes,
like potato leek soup.
Chive's like tall topsoil grass
and they are the thinnest member of alliums.
The subtle taste has made
them a popular food addition
in Central and the Western Europe.
Chives are used to help a bake potato or
add mild onion flavor to dips, salad or soup.
Green part of the chive has a mild onion flavor.
Chinese chive is good as a mild substitute for garlic,
and chive flowers are also edible.
Consumption patterns vary widely.
Onions are typically consumed in
larger quantities than other allium vegetable.
Obtaining exact estimates of
allium vegetable intake is really difficult,
because garlics, onions,
leeks and shallots are typically used
in mixed dishes in varying amounts,
and the shallots and chives may be used
in small amounts or as a pernicious.
Also, these vegetables are frequently used to add
flavor to stuff and then removed before consumption.
When dehydrated onion or garlics are added to processed
or prepared food and
the consumer may not be aware of such additions,
and therefore may not
report consumption of onions or garlics.
Therefore, all these reasons,
self-report of allium vegetable use may be unreliable.
However, data from
the Food and Agricultural Organization of
the United Nations show that
global per capita production of garlic and
onions have been increasing steadily since 1980.
Here, onions refer to the sum of
onions and shallots and green onions
and dried onions and then subtract.
Most pungent yellow and white onions have
typically been used worldwide for cooking;
however, consumption of sweeter onions, chives,
and shallots for uncooked use in the US is increasing.
In the US, onions
represent the third largest fresh vegetable.
In the US per capita consumption of
onion is about 22 pounds per year,
and The National Onion Association notes that
onion rings and onion blossom and
other onion appetizers are caramelized,
as onion and classic French onions
should remain popular restaurant use for onions.
In the past decade,
dried onions have gained popularity,
especially in fast casual dining,
such as pizza and sandwiches and salad.
The per capita onion consumption in the US has risen
over 70 percent in the last two decades from
12.2 pounds per person in 1982 to 21.9 pounds in 2017.
The average per capita onion consumption
across the world is
to approximately about 13.7 pounds,
and Libya has the highest consumption
of onions with about 67 pounds.
Garlic consumption has quadruple in the US since
1980 and now stands at about two pounds per capita,
and China has the highest consumption with
about 31 pounds per capita,
and about half of
the US garlic production is sold in
the fresh market and the other half is dehydrated.
This table shows the nutrient
in 100 gram of fresh allium vegetable.
As fresh vegetable, water makes up 58-90 percent,
and carbohydrate make up about 22 percent.
Allium is a decent source of dietary fiber
which accounts for 1.7-3.2 percent,
and they are rich in
soluble prebiotic fiber called the fructans.
Onions and garlics are the
particularly rich in soluble fiber,
which can help promote healthy gut bacteria.
Alliums also contain decent amount
of several vitamins and minerals,
including vitamin B, C,
folate, potassium, selenium, and manganese.
I'm not going through each numbers in this table.
In addition to nutrient,
alliums are among the main dietary stores
of bioactive plant compound.
Allium vegetables are rich source of
organosulfur compound which are thought
to be responsible for
the flavor and the potential health benefit,
and they also contain a high amount of flavonoid,
steroidal saponin,
we've talked about this in the last webinar,
and phytosterol and in others.
Among these, organosulfur compound may be
the major contributor to protect against the cancer.
Today, we will focus on organosulfur compound.
There again, most of the functional effect and
characteristic aroma in allium
associated with the organosulfur compound.
Organosulfur compounds are
organic compound that contain sulfur.
These compounds are
secondary metabolite biosynthesized for
defensive purposes against the stressor
formed when the plant tissue is damaged.
Organosulfur compound comprise approximately
0.5 percent of the dry weight of
onions and up to one percent
of the dry weight of a garlic.
Organosulfur compound also contributes
subtle flavor characteristic to wine,
nuts, and cheddar cheese and chocolate and coffee,
and tropical fruit flavor.
Organosulfur compounds are
reactive and heat instable component,
so by cooking their flavor will be reduced dramatically.
Most of the organosulfur compound are
fat-soluble and then some of them are water-soluble,
and once ingested, organosulfur compound are rarely
detected because they are
rapidly metabolized and excreted from the body.
Organosulfur compound are transformed
under different food processing condition.
The major constituent of the garlic and
chives and this is the sulfur compound alliin,
the major constituent of the onion,
shallot, or scallion is isoalliin.
These are also called the S-alkyl cysteine sulfoxide.
The alliin and isoalliin are odorless compound.
In home cooking, garlic cloves or onions
are often cut into small pieces or crushed into paste.
During cutting and crushing,
the enzyme called the alliinase is released and transform
alliin to allicin and thiosulfinate,
and these products are responsible
for garlic and onion odor.
These products are very unstable and
rapidly transformed to other sulfur compound.
The commonly available onion product,
include powdered or dried flake or essential oils and
naturally fermented or pickles or aged extract or paste.
In garlic or onion essential oil
which using this kind distillation method are
heat-induced to break down of allicin
or thiosulfinate generate the various mono-,
and di-, and trisulfide
as a result of the different distillation process.
Essential oils from alliums are highly valued for
their medical and biological functions
due to their organosulfur's content.
Powdered form of the garlic
and onions is widely sold in the market,
and freeze-drying is a major processing method.
During freeze-drying, tissues remain intact so there is
no enzyme-induced transformation happening
during cutting or crushing.
Therefore, the powder has a similar content
over organosulfur profile as the fresh alliums.
High heat, such as blanching, boiling, or microwaving,
deactivate that enzyme alliinase
and inhibit enzyme induced
transformation resulting in less amount of
heat sensitive organosulfur compound.
Pickling and fermenting alliums
also deactivate the alliinase
and eliminate the pungent flavor,
and this process will improve
flavor because during the fermentation,
lactic acid can be produced and
other fermented by-products will be produced.
However, long-term storage of a fermented product,
like over one year of
storage at refrigerator could reduce
the content of organosulfur compound by about 25 percent.
This page's slide tells us
the lay vial nature of organosulfur compound,
which are often transformed to
different structures depending on
the cooking and processing condition.
Good news is all kinds of
organosulfur by-product they are bioactive,
so any form of consumption
while cooked or in oil or water,
they are all active.
For food, I don't have to show
you dishes containing allium vegetables,
since almost every dish contains them.
On this slide, I just included fermented alliums.
These pickles are less pungent, as I mentioned,
that this acidic condition will
deactivate enzyme and contain
a rich aroma and flavor from
allium themselves and in the fermented product,
and they are good to serve with any type of food,
and they are also good to make
a salad dressing and sauce.
As you can see,
this is a garlic pickle.
These are pearl onion pickle, red onion pickle,
these are the shallot,
and these are chive or leek,
and as I mentioned,
chive flowers are also used as a pickle.
For this one, I just think [inaudible]
brine recipe that you can use for fermentation.
So the ratio of water, vinegar, sugar and salt is 5:9:9:1.
You can substitute salt with soy sauce
and you can add red pepper or pepper flakes or
peppercorns and other herbs as you prefer.
So mix all ingredient,
bring to a boil and set aside to cool,
then pour liquid over allium vegetables and
let stand overnight and
then you can store in a refrigerator.
It's really easy.
The dehydration process improves the food stability,
since it reduces the water activity considerably and
minimize the physical and chemical and
microbiological changes during storage.
As spices dry down in vegetables are widely used,
as I mentioned in previous slide,
freeze-drying is considered to be one of
the best methods for
organic sulfur compound and flavonoid content.
Hot air drying with or without
prior steaming branching method is also used for
allium dehydration and some people prefer
dried forms due to longer
storage time and less pungent flavor.
Allium vegetable dietary supplements are also available.
There are supplements containing one allium vegetable,
such as a garlic supplement,
onion supplement and chia supplement, etc.
These product contains about 350 to 700 milligram of
a dried vegetable and
garlic supplement is one of
the best selling allium supplement in this country.
There are supplements containing allium extract.
Several types of
extraction method are available commercially,
and each type provide a different profile of
organosulfur compound depending on how it's processed.
Not all preparations are standardized,
so each product may use different processing method.
Even standardized brand may vary with
the amount and the bioavailability
of organosulfur compounds that they provide.
So there are supplements containing
one allium vegetable extract or the mixed types.
The organosulfur content in these products ranges
between four to seven milligram.
There are also allium oil supplements.
[inaudible] product of allium vegetables
are usually dissolved in vegetable oil,
and again, some contains
one vegetable, some contains a mixed formula.
Their serving size ranges between one to five grams.
As I mentioned, the protective effect
of allium vegetables appear to be
related to and mainly through
the presence of organosulfur compound.
Several mechanisms have been proposed to explain
the colorectal cancer preventive or protective effect
of allium vegetables and related compounds,
allium inhibit metabolic activation of a carcinogen.
Carcinogen is the cancer-causing chemical.
Some chemical carcinogens do not become
active until they are activated by enzymes,
and alliums may inhibit
these enzyme activities and
inhibit the development of cancer.
Alliums also induce detoxifying enzymes.
The reactions by detoxifying enzymes
generally are to eliminate drugs,
toxin, and carcinogens from the body,
therefore, increasing the activity
of detoxifying enzymes may
help prevent cancer by
enhancing the elimination of a potential carcinogen.
In animal studies,
intake of allium extract or organosulfur compound,
increased the activity of
detoxifying enzyme in a variety of tissues.
Arresting the colorectal cancer cell cycle
is another major mechanism.
Most [inaudible] progress
through several cell cycle phases during cell division.
In normal cells the cell cycle is tightly regulated
to ensure correct gene replication
prior to cell division.
When gene factor occurs during
this replication, like DNA damage,
the cell cycle can be arrested at
checkpoints to allow for repair and
alliums and organosulfur compounds
halt the cell cycle and cannot progress to next phase,
eventually leading to inhibition
of a cancer cell growth and division.
Induction of a colorectal cancer cell apoptosis
is another prominent [inaudible].
Apoptosis is the process of
programmed death of a damaged or unnecessary cells.
In cell culture studies,
organosulfur compound induces apoptosis
when added to colorectal cancer cells.
In general, cancer cells
are growing faster and more aggressive.
In order to keep up their rapid growth,
invasive tumors must develop
new blood vessel by a process known as angiogenesis.
The anti-angiogenic properties of
several organosulfur compounds have
been observed in many studies
in cell culture in animal studies.
Also, many studies observe that alliums reduce
oxidative stress by neutralizing reactive oxygen species.
Although it's difficult to assess
exact amount of allium vegetable consumption,
numerous epidemiological studies
indicate an association of
a higher and frequently intake of allium vegetables
with decreased risk of colorectal cancer.
There are many case control studies
that have looked at the effect of alliums.
In a network of
Italian and Swiss case-control studies include
the 1037 colorectal cancer cases and then 2020 control,
the study assessed intake of onions and
garlic separately by a food frequency questionnaire,
the study found that
all levels of onion intake were associated with
a decreased colorectal cancer risk compared
to non-onion consumer and for garlic,
an immediate high intake were
associated with decreased the risk of colorectal cancer.
The association of onion and garlic intake
on colorectal adenoma was also assessed using
560 true colorectal cancer patients and
5,932 controls from cancer in the prostate,
lung and colorectal and ovarian cancer screening trial.
Researchers discussed that onion and garlic intake for
12 months prior to
screening using a food frequency questionnaire,
and they found the highest 20 percent
of garlic and onion intake was associated with
colorectal adenoma
compared to the lowest 20 percent.
Hospital-based case-control study was conducted
between June 2009 until
November 2011 in three hospitals with
833 patients and 833 controls.
In a North East Chinese population,
both men and women,
that the consumption of allium vegetable
is associated with a reduced risk of colorectal cancer,
whereas the World Cancer Research Fund and
American Institute for Cancer Research panel found
no statistically significant decrease to
the risk of colorectal cancer
with highest garlic intake in
two prospective cohort study
or three case studies showing some differences,
but the other three studies did not.
So the panel concluded that there was
no significant protective effect of
garlic or onion against the colorectal cancer.
There are many reviews and
meta-analyses who studied the effect of allium.
Meta-analysis reviewed 15 studies with 13,333 cases and
that meta-analysis concluded that there is
an association between high intake
of total allium vegetables
and reduced risk of
colorectal cancer and adenomatous polyps
or high garlic intake
alone reduced the risk of colorectal cancer.
Another review used US FDA's evidence-based review system
for the scientific evaluation of health claims.
19 humans for these were identified and evaluate
the strengths and the evidence that was
report the relationship routine,
garlic intake and reduce the risk of cancer.
And this review concluded that
there is a weak association
between garlic consumption and
reduce the risk of colon cancer.
Another meta-analysis examined about
colorectal cancer and stomach cancers
in relation through consumption of raw garlic,
cooked garlic or both.
The study concluded that high intake of
raw and cooked garlic is associated
with a protective effect against colon cancer,
colorectal cancer and stomach cancer,
approximately 30 percent lower colorectal cancer risk in
individuals were the highest garlic intake
compared to those with the lowest intake.
There are also some reviews finding
no association between alliums and colorectal cancer.
A meta-analysis that combine the data
from seven cohort and seven case-control studies
did not find a significant reduction
in colorectal cancer risk with the garlic intake.
Another meta-analysis of a five cohort,
including more than 4000 cancer cases,
they didn't find any association between
consuming the raw or cooked garlic
or supplement with a colorectal cancer.
Another meta-analysis of
eight different prospective cohort study
also found no association between
total allium vegetable intake and colorectal cancer.
There are only few intervention studies
related to allium vegetable.
Most of research are done with the observation study,
not many intervention studies.
One study examined the effect of
organosulfur compound called the diallyl trisulfide,
and they found that this organosulfur compound inhibits
colorectal cancer migration, invasion, angiogenesis.
This study also tested this component in mice,
and organosulfur compound depressed the growth
of human colorectal cancer tumors implanted in mice.
A small preliminary intervention trial
examined aged garlic extract.
Aged garlic extract is
a processed garlic product
and standardized with organosulfur compound.
This trial used 19 colorectal cancer patient
and 18 controls and examined
whether supplementation with the aged garlic extract
for one year affected tumor size and recurrence,
to boost the number and size of
the adenomatous polyps or significantly
reduced in patients given high dose of
aged garlic extract compared
to those given a much lower dosage,
which is 0.16 milligram per day.
Although I only included
the one study done with the aged garlic extra,
there are many animals that they tested with aged garlic
and most of them are showing their protective effect.
Let's look at the adverse effects.
The most commonly reported adverse effect of
oral ingestion of allium vegetables
are bad breath and body odor,
especially raw garlics and raw onions,
your breath and your sweat smells like garlic and onion.
Gastrointestinal symptoms have also been reported,
including heartburn and abdominal pain, belching,
nausea, vomiting, and flatulence which is gas condition,
and constipation, and diarrhea.
Garlic may also trigger
allergic response in some individuals, including asthma.
It's been reported from the workers,
so they are working in a garlic powder and dust.
Those people reported an allergic reaction.
Direct exposure has been reported to
cause contact dermatitis in some individual.
Contact dermatitis is a red,
itchy rash and more serious skin lesion
including blisters and burns.
It also been reported with
skin exposure to garlic for six or more hours.
The most serious adverse effect associated with
the intake of allium supplement
are related to the uncontrolled bleeding.
Several cases of serious post operative or
spontaneous bleeding associated with
allium supplement have been reported.
It is why that
many health benefits for
the allium vegetable consumption,
it's not recommended to consume
high doses of allium supplements
among patients that have a bleeding disorder
due to anticoagulant property.
Some studies have reported that alliums may
enhance anticoagulant effects of warfarin,
in some studies have no effect,
others have reported the potential additive effect on
blood clotting when allium supplements are taken together
with the other supplements such as
the high dose of fish oil or vitamin E.
So definitely more research needs to be done to determine
whether allium supplements are safe for
people on anticoagulants therapy.
Another drug interaction reported was the HIV medication.
One type of HIV medication called the Protease inhibitor.
So looks like a garlic supplement and an HIV medication,
and they are competing each other for
the same activation enzyme to be used in the body.
Protease inhibitors, if someone's on this one,
the garlic supplement is not recommended.
In summary, raw,
cooked, and dried allium vegetables have been used
as food ingredient and medicinal component.
Allium vegetables are rich sources of
organosulfur compounds which have been
extensively investigated for their health benefits.
Organosulfur compounds are transformed to
other organosulfur compound under
different food processing conditions.
All of these organosulfurs are bioactive,
therefore using various cooking and
preparation would provide
the diverse organosulfur compound.
In numerous pre-clinical studies,
a cell study in animal studies reported that
organosulfur compounds could exert antioxidant,
anti-inflammatory,
antimicrobial, anticancer,
and cardioprotective
activities in various experiments studies,
and several different types
of supplements are available commercially.
Again, each type provides a different profile of
organosulfur compounds depending on
how they were processed.
Several mechanisms have been proposed to
explain the anti-colorectal cancer effect
of allium vegetables and organosulfur compounds.
Allium and organosulfur components may inhibit
activation of carcinogen, induce detoxifying enzymes,
arrest cancer cell cycle,
induce the cancer cell death,
inhibit angiogenesis and reduce oxidative stress.
Current evidence from the majority
of observational studies does support
the association between high intake of
allium vegetable and reduce
the risk of a colorectal cancer.
According to the cells studies in animal studies,
the chemical components found in allium vegetable like
organosulfur compound and flavonoid can help
in reducing the growth of
the colorectal cancer cells and
tumor size in various experimental study.
Okay, that's what I have for today.
Any questions?